The Lemon program is an LALR(1) parser generator. It takes a context free grammar and converts it into a subroutine that will parse a file using that grammar.

Lemon is similar to the much more famous programs "YACC" and "BISON". But lemon is not compatible with either yacc or bison. There are several important differences: 

  o Lemon using a different grammar syntax which is less prone to programming errors.

  o The parser generated by Lemon is both re-entrant and thread-safe.

  o Lemon includes the concept of a non-terminal destructor, which makes it much easier to write a parser that does not leak memory.

The complete source code to the lemon parser generator is contained in two files. The file lemon.c is the parser generator program itself. A separate file lempar.c is the template for the parser subroutine that lemon generates. Documentation on lemon is also available.

Both the source code to lemon itself and the code that lemon generates are in the public domain. 

To see an example of how to use lemon, see the source code to the SQLite database engine. Lemon is maintained as part of the SQLite project. 

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 5260    6206  84.8% -lh5- ebf1 Aug  2 20:51 lemon.info
[generic]                42079   91680  45.9% -lh5- 0c70 Jul 16 18:14 lemon/lemon
[generic]                37067  141796  26.1% -lh5- 2f79 Jul 16 18:11 lemon/lemon.c
[generic]                11252   33449  33.6% -lh5- eec3 Jul 16 18:12 lemon/lemon.html
[generic]                 6753    7501  90.0% -lh5- 75cf Aug  2 20:51 lemon/lemon.html.info
[generic]                 7631   25819  29.6% -lh5- c0a0 Jul 16 18:11 lemon/lempar.c
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         6 files  110042  306451  35.9%            Aug  2 17:59